Neonatal encephalopathies are central nervous system disorders that are often accompanied by seizures. Seizures are one of the distinctive clinical manifestations of epilepsy, hypoxia, abnormal delivery, sleep deprivation and stress. Magnetic Resonance Imaging (MRI) plays a crucial role in the diagnosis and understanding of neonatal seizures. However, neonatal MRI evaluation is incomplete in assessing the entire neonate?s neurologic status, especially in regards to cortical functioning. In such circumstances, continuous video EEG can be useful as it provides important information about changes in frequency, synchrony, distribution and other characteristics of cerebral cortical activity. EEG is also a key modality in the understanding of developmental disabilities from early childhood. State-of-the-art EEG or dense array EEG (hdEEG ? 64 or more channels) has enabled the realization of EEG?s potential as a neuroimaging tool through source localization of normal and pathological brain activity and network dynamics. However, neither conventional EEG nor hdEEG are imaging (MRI or CT) compatible; hence, EEG electrodes are typically removed prior to any imaging study, with negative impacts on patient management because of extra delays and additional costs. The goal of this R01 project is to demonstrate the feasibility and safety of developing an imaging-compatible hdEEG net for cross-modal neonatal neural monitoring with artifact-free image quality. The proposed neonatal hdEEG net or ?NeoNet? will be designed by leveraging expertise in innovative 3D printing technology and thin film deposition at the A. A. Martinos Center, Massachusetts General Hospital. Rigorous safety assessment of specific absorption deposition rate and temperature will be performed using Finite Elements Method (FEM) simulations employing anatomically accurate male and female 2-week-old neonatal whole body models, which will be released to the public. Simulations will be validated by actual temperature measurements of induced RF heating using neonate phantoms wearing the NeoNet and compared against the gold standard of the phantom alone and against a commercial MR-compatible net built with traditional copper wire technology. Similarly, MRI data quality will be compared to data from the phantom-alone gold standard, and against data from the commercial hdEEG. CT data integrity will also be evaluated. The proposed NeoNet will enable inexpensive, noninvasive hdEEG and overcome current cross-modal safety and artifact issues that have so far severely limited the effectiveness of simultaneous hdEEG/MRI allowing researchers and clinicians to benefit from the high spatial resolution of MRI and the high temporal resolution of hdEEG. Furthermore, the technology will be light weight and small in size, taking advantage of advanced manufacturing technologies. The novel NeoNet will allow the study of brain function in healthy neonates in natural settings, as well as the understanding of different neonatal neural pathologies, such as epilepsy.